Perceived lactose intolerance in adult Canadians: a national survey

Although double-blind studies show that lactose-intolerant individuals can consume moderate quantities of milk products without perceptible symptoms, many who perceive that they are lactose intolerant limit or avoid milk products, potentially compromising calcium and vitamin D intakes. Adult Canadians are at risk of inadequate intakes of these nutrients, but no data exist on the prevalence, correlates, and potential impact of perceived lactose intolerance among Canadians. To address this, a Web-based survey of a population-representative sample of 2251 Canadians aged ≥19 years was conducted. Overall, 16% self-reported lactose intolerance. This was more common in women (odds ratio (OR), 1.84; 95% CI, 1.46-2.33) and in nonwhites (OR, 1.79; 95% CI, 1.24-2.58) and less common in those >50 years of age (OR, 0.71; 95% CI, 0.56-0.90) and in those completing the survey in French (OR, 0.74; 95% CI, 0.56-0.99). Those with self-reported lactose intolerance had lower covariate-adjusted milk product and alternative intakes (mean ± SE; 1.40 ± 0.08 servings·day(-1) vs. 2.33 ± 0.03 servings·day(-1), p < 0.001). A greater proportion used supplements containing calcium (52% vs. 37%, p < 0.001) and vitamin D (58% vs. 46%, p < 0.001), but calcium intakes from the combination of milk products, alternatives, and supplements were lower (739 ± 30 mg·day(-1) vs. 893 ± 13 mg·day(-1), p < 0.0001). Variation in self-reported lactose intolerance by sex, age, and language preference was unexpected and suggests that some groups may be more vulnerable to the perception that they are lactose intolerant. Regardless of whether lactose intolerance is physiologically based or perceptual, education is required to ensure that calcium intakes are not compromised.